1. Field of the Invention
The present invention relates to wireless communications; more specifically, to communications in a multi-path environment.
2. Description of the Prior Art
Many communications systems such as cellular systems and TDMA (Time Division Multiple Access) systems suffer from a performance loss which results from multiple signal paths between a receiver and transmitter. This problem is often referred to as intersymbol interference in communication systems that transmit information using symbols. Prior communication systems address this problem using a receiver that includes an adaptive equalizer which compensates for channel conditions such as multi-path conditions. Adaptive equalization techiques are discussed in "Adaptive Equalization for TDMA Digital Mobile Radio", J. G. Proakis, IEEE Transactions on Vehicular Technology, pp. 333-41, Vol. 40, No. 2, May 1991. When a system includes moving receivers, such as a receiver in an automobile, channel conditions may change relatively quickly and result in improper compensation by the receiver's equalizer. For example, an automobile's motion may result in improper compensation by losing or gaining signal paths at a rate that is faster than the rate at which the equalizer can adapt. As a result, when a signal path is lost, a receiver's performance is degraded by both the improper compensation of the receiver's equalizer and by the loss of signal power provided by the lost signal path, and when a signal path is gained, improper compensation may result in inter-symbol interference.